Some types of 3D sensing systems use active illumination, generated by pattern projecting modules. Among such systems there are systems that include light-coding and stereo 3D sensors, as well as hybrid systems combining both methods. However, for these types of 3D sensing systems, it is important that the pattern does not repeat itself along epi-polar lines, or at least is not repeated for part of the complete line. Yet, in some cases, the pattern projected by some modules is rather periodic.
In the known art, there are some solutions that propose solving the above problem by using a pair of projector modules, where their orientation is relative to position of the camera(s) used for 3D sensing, and is optimally determined so as to minimize pattern periodicity. In order to obtain that, a high accuracy is required in the module's rotation around the axis of sensing camera(s). In this solution, the angle accuracy is rather crucial in order to assure a non-repetitive pattern through the disparity range of the 3D sensor. Unfortunately, standard PCB assembly technologies implemented by the SMT (“Surface-Mount Technology) method, cannot guarantee the required accuracy.
The placement accuracy of standard printed circuit board (PCB) technologies cannot provide the required assembly precision of the projectors to allow good and consistent performance of the 3D sensors over large scale manufacturing. In many cases, when two projectors are required, the problem is not addressed by other means except of standard SMT assembly, which is a method for manufacturing electronic circuits in which the components are mounted or placed directly onto the surface of PCBs. The present invention seeks to provide a solution that overcomes this challenge.